This image shows the frame and lists the materials counts to construct the frame, including the sheathing material.
Note that the image shows a duplicate entry for number number of 2x6s needed. The number needed is 7. Refer to the materials list at the top of this guide.
Before screwing down the sheathing, double-check to make sure that frame is square by measuring the diagonals.
Once the diagonals measure the same, screw on the sheathing. Then, check the diagonal measurements one more time to make sure that the frame did not shift while you were screwing on the sheathing.
We left two openings on the bathroom side (as shown in the 3d model image in the beginning of this guide). These openings allow for the connection of drain pipes and the shower faucet.